“That’s the thing about space,” says Dinah MacQuarrie, a geologist and robotics expert working on the International Space Station in Neal Stephenson’s new work of science fiction, “Seveneves.” “So many smart people are so interested in it that it’s difficult to come up with a really new idea.”

A similar problem also applies to Stephenson’s think-piece of a novel. In “Seveneves,” the cult author of “Anathem,” “Snow Crash,’’ and his previous opus, “Reamde, “takes on familiar speculative territory: life in space. In some future time the moon mysteriously fragments into seven chunks. The spectacle becomes “the most extraordinary thing that humans had ever seen in the sky.”

That clunky prose is followed by a Hollywood blockbuster-ready set-up. According to “Doc”
Harris, a sort of Neil deGrasse Tyson-like popularizer of astrophysics, these big rocks will smash into each other until “an exponential hits the bend in the hockey stick curve.” Then comes “White Sky,” then “Hard Rain,” and all those moon rocks pummel earth for millennia and burn it to a crisp. People have less than three years to ditch their home planet. Just how many can get into space, and how long they will survive, takes up the bulk of Stephenson’s tale. The International Space Station, or ISS, now dubbed “Izzy,” becomes the nucleus of a modular lifeboat called the Cloud Ark, made up of “arklets,” designed by, that’s right, “Arkitects.” The inhabitants of the jury-rigged system of Habitrail-like tubes and struts go a little nuts.

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But on this ark, there’s no central Noah, nor do we settle on any cluster of protagonists. The dozen-plus costars, primarily female for reasons relating to the human race’s survival, feel like cardboard astronauts and cosmonauts around which Stephenson wraps his cognitive arabesques. Everyone talks in the same indistinguishable, procedural techno geek-speak. Sample line: “When we fire the main propulsion it will give us an off-axis thrust. If the scarf is oriented correctly, it will have tremendous control authority.” Stephenson’s idea of character description? A C.V. of Ivy League stops and post-doc appointments.

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As in his other novels, Stephenson delights in descriptions of processes and functionality. Why things work the way they work. What happens when they don’t work. There are pages of passages about mass ratio and thrust, how air pressure works on hatches and feels on the inner ear, how humans adapt to life in zero gravity and redirect the orbit of a comet to mine it for ice. It’s as if Stephenson, in writing a novel about a hot-shot chef, instead of focusing on her emotional life, explained in excruciating detail how she produced a seven-course meal using molecular gastronomy. There’s scant popping inside a character’s mind or delving into the interpersonal tension or desire between two people.

In Stanley Kubrick’s space epic “2001: A Space Odyssey,” a radical film cut transforms a bone thrown by an ape man into a space station. Stephenson tosses similar caution to the wind when he ends the Cloud Arc story arc two-thirds of the way in, jumps 5,000 years into the future, and returns to earth. That’s a tough leap to ask readers to make, let alone digest new lexicons of people and jargon — Kath Two, TerReForm, Teklans — and a fresh lattice-work of world-building and imaginary futuristic structures so minutely described that special-effects designers could draw up the blueprints.

Still, “Seveneves” can be fascinating. The intrigue gains traction as rival factions vie for political control in the power vacuum of space. Characters have capital B “Big” conversations about the ethics of cloning and DNA repair. The third act posits clever thought experiments about race, cultures, and genetically engineered personality. Insights into the human character shine like occasional full moons to keep our attention. “If you hid your feelings well enough,” Stephenson writes, describing Harris, “it actually changed you.”

Too bad we don’t care much for the characters Stevenson uses as mouthpieces for his shiny ideas. Rather than “novel,” perhaps the genre of “fictional treatise” is a better name for this largely expository work. That genre might liberate Stephenson from the character troubles many read fiction for. So would a training manual for budding NASA Mission Control geeks.